Friction facing



UNITED STATES PATENT OFFICE. I

FREDERICK C. STANLEY, OF BRIDGEPORT, CONNECTICUT, .ASSIGNOR TO RAYBESTOS COMPANY, OF BRIDGEPORT, CONNECTICUT, A. CORPORATION OF CONNECTICUT.

FRICTION FACING.

Specification of Letters Patent. Patented luay 30, 1922. I

No Drawing. Original application filed September 24, 1919, Serial No. 325315; Divided and this application filed August 28, 1920. Serial No. 405,508.

To allwkomz'tmyconcem:

Be it known that I, FREDERICK C. STAN- LEY, a citizen of the United States, residing vented certain new and useful Improvements I in Friction Facings, of which the following is a specification.

This application is a division of an original application filed by me, on September 24, 1919, Serial No. 325,915.

This invention relates to improvements in friction facings and refers more particularly.

to a clutch facing or brake lining adapted for use in motor vehicles. The invention is directed to a novel friction facing made from felted unwoven asbestos fibre saturated with a binder. r

The object of the invention is to provide a friction facing having a maximum tensile strength and hardness so that it can withstand the shocksto which these faclngs are subjected in a motor car and also will have sufficient resistance to abrasion; while at the same time it has the proper coefficient of friction. It is also-necessary that the binder in these facings must be unaffected by oil or;

water in use, which object'is accomplished by the present invention without in any Way detracting from the other characteristics.

The process for making these friction facings may be carried out as follows: Asbestos fibre, preferably the short or low grade fibre is first ground in a suitable .grindingmachine or cutter. The ground material is, then put into a heater mixed with the water or other solution'jandbeaten into a pulp. The pulp is then delivered to a paper making machine, as'for example, a wet board ma- "chine and formedinto sheets 01' boards of suitable width and thickness. This, forms an unwoven felted sheet.

As a feature of the: invention, there is mixed with the pulp in the beater a sulphurizing agent, as for example, sulphur, lead sulphideor analogous sulphides. In Us ing sulphide as a sulphurizing agent, the amount employed is approximately 1.6 per cent by the weight of the asbestos fibre although this can be varied according to the characteristics of the product desired. This sulphurizing agent facilitates or hastens the cure of the binder and adds to the strength 'of the product and also converts the binder into a form insoluble by oil or water. also tends to produce a uniform curing throughout the mass during the curing operation hereinafter described. It is to be noted that this reagent is put into the pulp before the formation of the sheet and not during the saturating and curing steps of the process.

After the sheets or boards have been 3 formed-as described, they are subjected to hydraulic pressure in suitable presses and are then hung up to dry in adryin room of sufiicient temperature to remove t e water.

'The sheet is then calendered to the desired thickness. and the friction facings are then cut outof the sheet. I jected to sufficient pressure in the calender to obtain as much tensile strength in the dry sheet as is feasible. The friction facings,

whether clutchrings or brake linings are now ready fforsaturation. The saturating tank is filled with a binder. This binder may consist of 94 per cent of linseed oil, 6

per "cent of gilsonite in the solution in the oil thinned. with gasoline to about 33 Baume gravity. The friction facings are then immersed while suspended on suitable rods in this binder solution for a period of half an hour. The friction facings are then removed and put 1n a closed steam oven and maintained at a temperature ofabout 200 F. to

drive oil the gasoline, which gasoline may be recovered and saved; This steam treatment is preferably continued from two to three' hours. The friction facings are then re-. moved to a closed baking oven, where they are subjectedto a temperature ofabout 250 F., for a period of twelve hours. The facings are then taken out of the oven-and im-' mersed inanother saturating-tank contain- .ing a solution of 66 per cent of linseed oil and The sheets are sub- 70 The friction facings are papered to micrometer size and to get a smooth finish to the facing. The facings are now ready for use.

I have given above. an illustration in which th process is actually carried out in It is to be undercommercial operation. stood that the temperature and length of treatment are subject to reasonable variations depending on the flexibility and strength required in the finished product. Also oils other than linseed oil may perhaps in certain cases be used and other asphalts substituted for gilsonite.

-During the baking operation, the linseed oil, du to the presence of the water in the oven and also to the sulphurizing agent of the sheet is sulphurized to produce a tough hard binder. oil before the baking treatments is practically 100% in the gasoline while after the baking treatments it is very -mate'rially re- 'diiced; and in fact the baking operation may madeby this process is in excess of 3000 to 4000 lbs., upwards in tensile strength, over that heretofore obtained from any unwoven saturated friction facing and is even stronger The solubility of the linseed than a Woven sheet. The Brinnell hardness also is proportionately increased over the friction facings heretofore made and is above 15. It is to be noted that in the baking operation, the .reaction develops autogenous heat or in other words exo-thermic and care must be taken to prevent the mate: rial from becoming so highly heated as to catch fire. This exo-thermic reaction results in the fact that the sulphurization is of such 'a character as to generate heat in addition to that externally applied. This exo-thermic reaction of sulphurization is Well known in other arts, as for example, in the manufacture of airblown asphalt from petroleum residuum.

I claim as my invention:

1. A frictionfacing composed of unwoven sheet asbestosfiber, saturated with a baked sulphurized linseed oil binder.

2. A friction facing composed of unwoven sheet asbestos fiber, saturated with a baked sulphurized binder.

3. A friction facing composed of unwoven sheet asbestos fiber, saturated with a baked sulphurized binder, and having a Brinnell hardness in excess of ten and a tensile strength in excess of twenty five hundred.

4. A friction facing composed of unwoven sheet asbestos fiber, saturated with a baked sulphurized linseed oil binder, and having a Brinnell hardness in excess of ten and a tensile strength in excess of twenty five hundred. v

FREDERICK C. STANLEY. 

